Properties and States of Matter Multimedia Lesson

Properties and States of Matter

Science, Grade 6

Table Of Contents: Properties and States of Matter

1. Introduction to Matter

2.1. What Is Matter?

Matter is anything that takes up space and has mass. Everything around us that we can see is made up of matter. Our food, clothing, homes, possessions and even our bodies are all composed of matter.

2.2. Matter and Substances

A substance is a type of matter that is pure and has a specific chemical makeup. For example, salt, sugar, and water are all substances with precise chemical compositions. Although there are numerous examples of pure substances, most of the matter around us is made up of many substances. Just think of all the substances and ingredients found in the foods we eat every day.

2.3. Properties of Matter

Matter can be described as having physical and chemical properties. Physical properties would include things like mass and color. For example, a piece of wood has physical properties that can be measured and observed. Chemical properties are related to how matter can react and change into other materials. Chemical properties of this wood are that it is flammable, and if it is burned, it will change to ash and smoke.

2.4. Physical Properties

A physical property of matter is a property that can be observed or measured without changing the composition of the matter. Some examples of physical properties include color, texture, flexibility, density, mass, and magnetism. The states of matter, solid, liquid or gas, are also physical properties.

2.5. Chemical Properties

A chemical property of matter is a property that describes the ability of the matter to react to other substances and change into different substances. Reactivity and flammability are both chemical properties. A chemical property of iron is that it reacts with oxygen in the air to form iron oxide, or rust. Another example is the flammability of fossil fuels, which release carbon dioxide gases when they are burned.

2. Pause and Interact

3.1. Review

Use the whiteboard text tools to complete the activity.

3. Classes of Matter

4.1. Elements

Elements are the most basic forms of matter. Aluminum, sulfur, iron and oxygen are all examples of elements. These are pure substances that cannot be broken down into simpler substances. Scientists have identified over 100 elements that are present in our universe. Each element is made up of one type of atom which determines its properties. The Periodic Table groups elements by their atomic number. Each element is represented by a chemical symbol.

4.2. Atoms

Atoms are the building blocks of elements. Every element is made up of atoms that have a unique structure. For example, an oxygen atom contains eight protons and eight neutrons in its nucleus. Eight electrons circle the nucleus in an electron cloud.

4.3. Molecules

A molecule is the chemical combination of at least two atoms. Many elements occur in nature as molecules, not as single atoms. Oxygen typically occurs as a molecule made up of two chemically bonded atoms, and is written in a chemical formula as O2. A molecule of water is composed of three chemically bonded atoms. The formula for water is written as H2O.

4.4. Compounds

A compound is a pure substance made up of two or more different elements that are chemically combined in an exact ratio. The chemical formula of a compound tells you which elements make up the compound and how many atoms of each element are found in a single molecule of the compound. Water is a compound that has a ratio of two hydrogen atoms to every one oxygen atom. If this ratio is changed to two hydrogen atoms to every two oxygen atoms, a different compound is formed. This compound, hydrogen peroxide, has different properties than water. It is used as cleaning agent, and you would not want to drink it!

4.5. Mixtures

A mixture is the physical combination of two or more substances. Mixtures can be made of compounds and elements. The substances in a mixture are not chemically combined, and they are not found in an exact ratio. Imagine a mixture of nuts in a bowl. The ingredients keep their individual properties and can be separated. This nut mixture is called a heterogeneous mixture, because you can see the individual substances. In a homogeneous mixture, like paint, you cannot see the individual parts that make up the mixture.

4.6. Solutions

A solution looks like a single substance, but it is actually a homogeneous mixture made up of two or more evenly distributed substances. For example, when salt is mixed with water, the salt particles dissolve, or mix evenly, with the water particles. The salt, which is the substance that dissolved, is called the solute. The water, which caused the salt to dissolve, is called the solvent. Solutions can be found in all the different states of matter. Solutions can be liquids like anti-freeze, or gases like the air we breathe, and even solids, like brass.

4.7. Concentrations of Solutions

Some solutions are considered to be concentrated while others are considered to be dilute. The concentration of a solution is the amount of solute in a given amount of solvent. Concentrations are often measured in grams per milliliter. A concentrated solution has more solute in it than a dilute solution.

4.8. Suspensions and Colloids

If the particles that are dispersed throughout a mixture are large enough to be seen and they scatter or block light, then the mixture is called a suspension. Eventually these particles will separate and settle out. For example if you mix sand in a beaker of water, and then let it sit for a while, the sand particles will settle on the bottom of the container. Colloids are a type of mixture in which particles are too small to see, but they are large enough to scatter light and be filtered. Milk, gelatin, and whipped cream and many of the foods we eat are considered colloids.

4.9. Separating Mixtures

The substances in a mixture are not chemically bonded together and therefore can be separated using a variety of techniques, depending on the compounds and elements that make up the mixture. Magnets can be used to separate a mixture of nails that is made of iron and aluminum. Some mixtures made up of liquids and solids can be separated using filters. Distillation is a process used to separate substances that have different boiling points, like water and salt. A centrifuge is a machine that spins mixtures at high speeds. It can be used to separate substances by their densities.

4. Pause and Interact

5.1. Review

Use the whiteboard text tools to complete the activity.

5. States of Matter

6.1. States of Matter

Matter can exist in three different physical forms—solid, liquid or gas. We are all familiar with the forms of water—ice, liquid water and steam. These different forms are called the states of matter. The particles within matter interact with each other in different ways and determine if the matter is a solid, liquid or gas.

6.2. Solids

Solid matter has a definite shape and volume. Think about a bowling ball. You can pick it up, move it and drop it, and the shape always remains the same. The ball is a solid. The particles that make up a solid are packed tightly together in a fixed position. The particles themselves vibrate, but they do not move out of position.

6.3. Crystalline and Amorphous Solids

Solids can be classified as crystalline or amorphous. In crystalline solids, such as quartz or salt, the particles have a regular repeated pattern and a definite geometric shape. When crystalline solids are heated, they have a precise melting point. Amorphous solids, such as glass and rubber, are made up of particles that are arranged randomly, and they do not have a precise melting point.

6.4. Liquids

Liquid matter can change its shape, but it always has a definite volume. For example, if you pour 200 ml of milk from a carton into a measuring cup and an equal amount into a flask, the shape of the liquid will be different in the two containers, but the volume will stay the same. Similar to a solid, the particles in a liquid are packed closely together. However, unlike a solid, the particles in a liquid can slide past each other. This sliding motion allows a liquid to flow, or be fluid, and take on the shape of its container.

6.5. Surface Tension

Many liquids, such as water, form droplets. These droplets are caused by surface tension, which occurs when the molecules at the surface of the liquid form a strong attraction to each other and to the water molecules below them. This attraction can form a layer on the surface of the liquid. Surface tension is what allows lightweight insects to actually walk across the surface of a pond. The surface tension of different liquids varies. For example, alcohol has a lower surface tension than water.

6.6. Viscosity

Viscosity is a property of liquids. Basically, viscosity means a liquid’s resistance to flow. Liquids with higher viscosity flow more slowly, like honey. Liquids with lower viscosity flow more quickly, like water. Here are some other examples of liquids and their relative viscosities.

6.7. Gases

Gas particles move in all directions, and are only limited by the container they are in. Unlike solids and liquids, gas particles have a lot of empty space between them. Gases can change both shape and volume. Scientists discovered that the temperature, volume and pressure of a gas are all related. Changing one of these factors, affects the other factors.

6.8. Boyle’s Law

Robert Boyle was a scientist that studied gases and the relationship between pressure and volume. Boyle’s law states that, for a gas that is at a constant temperature, the volume is inversely related to the pressure. An example of Boyle’s Law in action is the increasing volume of bubbles as they rise from an area of high pressure to an area of low pressure. A scuba diver at the bottom of the ocean releases air bubbles. As the bubbles rise, the pressure inside the bubbles decreases. This decrease in pressure results in an increase in volume within the air bubbles, and the bubbles get larger.

6.9. Charles’s Law

In the late 1700s a scientist and inventor named Jacques Charles helped create the first hydrogen-filled balloons. He discovered that the volume of a gas, such as hydrogen, will increase as the temperature of the gas is increased. Charles’s Law states that, for a fixed amount of gas at a constant pressure, the volume will change in direct proportion to a change in temperature. For instance, in a hot air balloon, as the gas inside the balloon is heated and the temperature increases, the volume of the gas expands, and the balloon gets larger.

6. Pause and Interact

7.1. Review

Use the whiteboard text tools to complete the activity.

7.2. States of Matter

Follow the on-screen instructions to complete the activity.

7. Changes of State

8.1. What Is a Change of State?

A change of state is when matter changes its physical form, such as when a solid melts to form a liquid, or when a liquid is heated to form a gas. Changes of state are physical, not chemical, changes. The matter itself does not change its chemical composition.

8.2. Physical States and Thermal Energy

The physical state of matter is related to the thermal energy of the particles and the amount of movement of the particles. Matter that is solid has the least amount of thermal energy and the particles have very little movement. Liquids have more thermal energy and the particles exhibit more movement. Gases contain the most thermal energy and the particles are in constant motion.

8.3. Adding and Removing Thermal Energy

Changes of state occur when matter gains or loses thermal energy. For example, a liquid can gain thermal energy when it is heated. The particles move faster, and the liquid matter changes to a gas. If a liquid is cooled, it loses energy and the particles slow down. The liquid then changes to a solid. Changes that occur when energy is added to matter are called endothermic, and changes that occur when energy is removed or lost are called exothermic.

8.4. Changing States of Water

We are familiar with the changing physical forms of water in our everyday life. This diagram shows the different physical forms of water and the processes that occur when water changes states. Melting and evaporation occur when heat or thermal energy is added. Freezing and condensation occur when heat or thermal energy is removed.

8.5. Melting

Melting is the process of changing from a solid to a liquid state. When thermal energy is added to the solid, the temperature rises and the particles vibrate faster and faster. The particles reach a point when they move out of their fixed positions and the matter becomes a liquid. The temperature at which the solid becomes a liquid is called the melting point. Different materials have different melting points.

8.6. Freezing

Freezing is the process of changing from a liquid to a solid state. It is the opposite process of melting. When thermal energy is removed or lost from a liquid, the temperature becomes cooler and the particles move more slowly. When the particles reach a point when they are no longer moving and are in fixed positions, the matter becomes a solid. The temperature at which the liquid becomes a solid is called the freezing point, which is actually the same temperature as the melting point.

8.7. Vaporization

Vaporization is the process of changing from a liquid to a gas. When thermal energy is added to a liquid, the particles move faster and faster, until they form a gas. There are two types of vaporization, evaporation and boiling. Evaporation occurs when particles on the surface of a liquid are moving fast enough to escape into the air as gas. Boiling occurs when the particles throughout a liquid are moving fast enough to become gas. Water molecules that are heated will vaporize and form bubbles that rise to the surface. The boiling point is the temperature at which a liquid begins to boil.

8.8. What Affects the Boiling Point?

The boiling point of liquids is different for different materials. The molecular structure of a substance determines how much energy is needed for it to change from a liquid to a gas. Air pressure also affects the boiling point. When the air pressure surrounding the liquid is higher, more energy is needed for the particles to break free and change to gas. If the air pressure is lower, then less energy is required, and the liquid will boil at a lower temperature.

8.9. Condensation

Condensation is the process of changing from a gas to a liquid. It is the opposite process of vaporization. An example of condensation is when we see water droplets form on the surface of a cold glass. When the air around the glass is cooled, the particles of water vapor in the air move more slowly. The particles begin clumping due to molecular attraction, and the gas changes to liquid water droplets. The temperature at which a gas becomes a liquid is called its condensation point, and it is the same temperature as its boiling point.

8.10. Sublimation

Sublimation is a process that occurs when a material changes from a solid directly into a gas. An example is dry ice, which is extremely cold and is composed of carbon dioxide. When dry ice is removed from a freezer, it acquires thermal energy from the warm air surrounding it, and the solid changes directly to a gas. The cold gas causes water vapor in the air to condense and form fog.

8. Pause and Interact

9.1. Review

Use the whiteboard text tools to complete the activity.

9. Measuring Matter

10.1. International System of Units

Scientists use the International System of Units, abbreviated SI units, for measuring matter. The SI unit for mass is a kilogram and for length is a meter. When measuring volume, the liter is the most commonly used unit. Prefixes are used to indicate smaller or larger units. For example a centimeter is one- hundredth of the length of a meter. SI units enable scientists to measure matter and share data in a consistent and accurate way.

10.2. Mass and Weight

An object’s mass refers to the amount of matter an object contains, while an object’s weight is the measure of the effect of gravity on its mass. The mass of a person is the same on the Moon and the Earth, but the person weighs less on the Moon than the Earth because the Moon exerts a smaller gravitational force than the Earth.

10.3. Volume

Volume is the amount of space that matter occupies. The volume of liquids and gases are typically measured in liters and milliliters. Solids are often measured in cubic centimeters. One cubic centimeter is equal to one milliliter. To calculate the volume of a solid, measure and then multiply its dimensions. A box with a width of 25 cm, a height of 4 cm, and a length of 45 cm, has a volume equal to 4,500 cubic centimeters. To find the volume of an irregularly shaped object, such as a rock, scientists sometimes submerge the object in a container of water to see how much water is displaced. The rise in the water level indicates the volume of the rock.

10.4. Density

Matter can also be described by measuring its density. Density is the mass of an object in a given volume. To calculate density, divide an object’s mass by its volume. The unit for density is grams per cubic centimeter. For example, a piece of aluminum with a mass of 500 g and volume of 200 cm3 has a density of 2.5 g/cm3. A piece of iron with the same volume has a mass of 1500 g. Iron’s density is 7.5 g/cm3.

10. Pause and Interact

11.1. Review: Pulley Types

Use the whiteboard text tools to complete the activity.

11. Vocabulary Review

12.1. Properties and States of Matter Vocabulary Matching

Scientists use the International System of Units, abbreviated SI units, for measuring matter. The SI unit for mass is a kilogram and for length is a meter. When measuring volume, the liter is the most commonly used unit. Prefixes are used to indicate smaller or larger units. For example a centimeter is one- hundredth of the length of a meter. SI units enable scientists to measure matter and share data in a consistent and accurate way.

12. Virtual Investigation

13.1. Gas Laws

Scientists have discovered that the temperature, volume and pressure of a gas are related. In this virtual investigation you will study the properties of gas by experimenting with these three different variables. By holding one of these variables fixed, or constant, you can explore the relationship of the other two variables.
The investigation will take place in a simulated lab that contains a cylinder filled with gas molecules as well as a thermometer, pressure gauge, hot plate and weights. In three different scenarios, you will change an independent variable in order to learn more about how the gas properties are related. During the lab you will collect data, plot graphs, make observations and draw conclusions. You will also identify the scenarios that demonstrate Boyle’s law and Charles’s law.